Industrial valves, such as those involved in fluid transmission lines, are typically actuated by the rotation of a stem. Valve actuators are frequently manufactured by different entities than the valves and typically operate by rotating a provided valve stem.
Valve stem covers are utilized for enclosing an exposed valve stem and a valve stem/valve actuator interface in order to protect the stem and interface area from wind, rain, dust, debris and/or generally the environment.
Gate valves and sluice valves can involve quite long threaded stems. Their stem protectors can concomitantly be quite tall and/or long and heavy. See Figure on page D118 of EIM Controls Technical Reference Handbook, First Edition, attached to Information Disclosure Statement.
It is important for the long term trouble free operation of most valves and their actuators to keep the contact area between the actuator and the valve stem not only clean but lubricated. This attention to the actuator/stem interface area is particularly pertinent for gate and sluice valves where the actuator provides a mating threaded nut for running on long threaded stems. When the contact area between an actuator nut and a threaded stem is not maintained adequately cleaned and lubricated, corrosion and disintegration can result.
A field case study performed by the instant inventor in 2004 documented the corrosion and disintegration that could result when the contact area between an actuated nut and a threaded stem was not maintained adequately cleaned and lubricated. In that case an actuator was returned to the instant inventor in March 2004 to disassemble and study the wear on the electrical and mechanical components occasioned in the field since having been shipped to the customer in 1989. The actuator had been located awkwardly on a structure above a gate. Lack of proper lubrication was determined to be the apparent cause for actuator failure. A bronze worm gear was worn due to sliding friction. It was determined as part of the problem that the actuator installation at the job site was awkward, it was difficult to access, and the importance of lubrication was apparently not fully understood. Water in the gear box together with a lack of lubrication were determined to be the causing factors.
Valves, including industrial gate valves and sluice valves, are sometimes situated in hard to reach locations. The threaded stem of a gate or sluice valve, in addition, may be several feet long, resulting in a large and heavy valve stem protector. Lubrication traditionally entails removing the valve stem protector followed by application of lubricant to the contact area between the stem and the actuator nut and then replacement of the stem protector. When the location is difficult to reach and/or the protector is heavy and large, those charged with valve maintenance may forego the actuator/stem lubrication process. This can have unfortunate and undesirable consequences.
The prior art has offered an automated stem lubricator. (See above referenced Figure on page D118.) This lubricator was never significantly commercially successful, presumably due to its complexity and expense. The prior art automated lubricator did not provide any special means for draining any unwanted water or fluid that collected inside the protector, such as by condensation, or that became trapped in the valve stem/actuator cavity or interface area The automated stem lubricator was designed to place, at predetermined time intervals, a small amount of oil from a reservoir into a valve stem/actuator nut contact area, using an oil port located midway up a stem protector sleeve.
The instant invention provides an improved valve stem protector and improved method for lubricating, as well as method for draining unwanted trapped water or the like out of the valve stem/actuator nut cavity or interface area The instant invention provides for lubrication without the removal of the protector, optionally from a distance, eliminating a necessity for reaching an awkward location and/or for removing a heavy large valve stem protector. The instant invention provides, in addition, a further advantage of a draining space or port or channel, for draining unwanted water or trapped fluid out of the valve stem/actuator interface area and/or away from locations sensitive to corrosion. Lubricating grease tends to trap water in the actuator/stem interface area. Preferred embodiments of the instant invention provide a channel, preferably between an inner and an outer sleeve portion of a stem protector assembly, wherein unwanted fluid may naturally drain away or be displaced to drain away. Fresh lubricant can be used to flush water that has collected in the interface area to that channel.
Prior art stem protectors frequently glue an outer sleeve to an inner sleeve and screw the inner sleeve to the valve actuator. If lubricant or grease fills the actuator/stem interface area, no space or channel or port is available or otherwise provided for unwanted fluid drainage from inside the sleeve assembly to outside the sleeve assembly. To flush out water that condensed inside or leaked in and became trapped, the whole protector had to be unscrewed and removed.
To the extent unwanted fluid or water comprises condensation formed on the inside of a protector sleeve, in preferred embodiments of the instant invention the condensation can drip down the inside of the protector sleeve into a space or channel between the protector sleeve and an inner sleeve. The space or channel provides for the fluid to drain to the outside of the sleeve assembly.
To the extent unwanted fluid or water collects by some other means on the inside of the inner sleeve and is trapped down in and around the contact area of the interface of an actuator nut and a valve stem, in this latter case in preferred embodiments a periodic forcing of lubricating fluid into the cavity of the contact area between the actuator nut and the valve stem can force the unwanted fluid that collected therein upward. As lubricant is continued to be applied the unwanted fluid will eventually overflow the inner sleeve and pass out of the assembly through channels between the inner and the outer sleeve. Alternately, the fluid could pass through a port of the inner sleeve.
In preferred embodiments of the instant invention, as in the prior art, the outer sleeve is preferably a tough clear plastic cylinder capped at its upper end. The cylinder preferably fits over a lower inner cylindrical sleeve, typically formed from aluminum. The inner sleeve is typically externally threaded to fit into internal threads provided by a valve actuator and also contains a shoulder upon which the outer protective cylinder can rest. The outer cylinder could be clamped to the inner cylinder or it can also simply rest on top of the inner sleeve, substantially held in place by the stem and gravity. The inner cylindrical sleeve in preferred embodiments contains vertical channels (or channels at least with vertical components) in its outside circumference. The vertical component channels provide for drainage of fluid down the outer wall of the inner cylinder, between the inner and outer sleeves or cylinders, largely propelled by gravity. Drainage could also be enhanced or propelled by pressure or by a capillary effect. The bottoms of the vertical component channels preferably open below the shoulder holding the outer cylinder, thereby permitting fluid to drain to the outside of the sleeve assembly. Preferably two lubrication ports would be provided in the lower or inner sleeve or cylinder.
A specially designed lubrication port could itself provide for drainage outward of fluid such as water. A drainage port is understood broadly to encompass openings and channels as well as a lubricant port.
Suction or pressure could be applied to a port or ports to accomplish or enhance drainage.
A solvent could be applied through a port to the inside of the assembly to pressure or blow out old lubricant and water, prior to applying fresh lubrication.
It is envisioned that the lubrication ports are preferably connected or connectable to lubrication hoses so that if the location of a stem protector assembly is not favorable for convenient hands-on work, lubricant could be provided from a distance through the hoses or lines attached to the ports.
Lubrication could be provided by either a manual lubrication applicator or a powered lubrication applicator.
Again, in operation, as discussed above, as lubricant is applied into a cavity or area wherein an actuator nut contacts stem threads, rising lubricant preferably forces any fluid that has collected therein upwards until the fluid vents through a space provided by the assembly, such as channels between an inner and outer cylinder.